1. Field of the Invention
The invention relates in general to a power adaptor system and method, and more particularly to a power adaptor system and method capable of selecting an operating mode.
2. Description of the Related Art
The number of market-available electronic devices with diversified functions is ever-increasing along with advancements in technology. These electronic devices not only fulfill demands of people but also prevail in the daily life to bring indispensible conveniences to life.
Among the electronic devices, laptop computers are common equipment offering both working and entertainment functions. Although a laptop computer is equipped with a battery, it is known that the amount of electricity provided by the battery is limited. When the laptop computer is under a long-term use, a transformer is required as a power adaptor side for transforming an AC voltage to a DC voltage, which is then provided to the laptop computer.
DC voltage inputted into a laptop computer has gradually developed towards a consistent value range, with most laptop computers applying a 19V DC voltage. However, computer manufacturers frequently provide an identification function using different techniques to ensure that users do not connect transformers of other manufacturers to laptop computers of a own brand. That is, a system side first identifies whether a connected transformer is provided by the same manufacturer of the laptop computer. If not, the laptop computer will not utilize electric power of the transformer produced by another manufacturer.
FIG. 1 shows a schematic diagram of transmission wires of a prior art, in which an additional conducting wire is adopted for confirming a type of a transformer. A conventional adaptor 11 has two conducting wires for respectively providing an input DC voltage Vdd and a ground voltage GND to a laptop computer 13.
To determine whether a transformer connected to the laptop computer 13 is correct, an identification function for the adaptor 11 is provided by certain manufacturers. One approach for identifying the transformer is via an identification signal Vid generated by an additional conducting wire. After reading the identification signal Vid, only when the identification signal Vid matches to an identification signal stored in the laptop computer 13, the laptop computer 13 then utilizes the power provided by the adaptor 11.
Although providing the additional conducting wire offers a function of identifying a transformer, such approach nevertheless results in a rigid and inflexible manufacturing process.